Washington: The US has formally raised its concerns with the Chinese authorities about Google's allegations of a cyber spying campaign originating in China.

"We did raise our concerns with the Chinese about the allegations and asked them to take a look into them," State Department spokesman Mark Toner told reporters.

However, he did not give any details of how this issue was raised with the Chinese authorities.

Google said on Wednesday it was hit by a cyberspying campaign that appeared to have originated in Jinan, capital of the eastern Chinese province of Shandong.

China on Thursday had said it was "unacceptable" to blame it for a cyber spying campaign which Google said had targeted the Gmail accounts of senior US officials, military personnel, journalists and Chinese activists.

"We still have no indications that anyone here was targeted," Toner said in response to a question.

"There's an ongoing investigation, so I'm not going to attempt to characterise as we move forward, except to say what I just said, which is that we take them seriously and express that concern to the Chinese," he said.